Subsidiary Formation of Trihalomethanes by Oxidation Decomposition using Sodium Hypochlorite of Liquid Waste Containing Cyanide

Abstract

Under the conditions of the oxidation decomposition reaction using sodium hypochlorite of liquid waste containing cyanide, methyl ketones and certain other compounds with bromide often afforded the reaction products, such as trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane (referred to as “ trihalomethanes” ). Trihalomethanes are regulated as environmental pollutants. In order to control the formation of trihalomethanes, threfore, the formation conditions were examined. Using acetone, one of the trihalomethane precursors, the experimental results indicated that most of trihalomethanes were given by the first step reaction of the cyanide decomposition, and that large amounts of tribromomethane were produced on approximately pH 12. However, some of the formation conditions for trihalomethanes were different from those for the cyanide decomposition. It might mean that the formation reaction could be suppressed by the accurate control of the cyanide decomposition.